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58 lines
2.4 KiB
58 lines
2.4 KiB
5 years ago
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title = "Things I Learnt The Hard Way - Cognitive Cost Is The Readability Killer"
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date = 2019-06-26
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[taxonomies]
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tags = ["en-au", "books", "things i learnt", "cognitive dissonance", "cognitive cost"]
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+++
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"[Cognitive dissonance](https://en.wikipedia.org/wiki/Cognitive_dissonance)"
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is a fancy way of saying "I need to remember two (or more) different and
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contradicting things at the same time to understand this." Keeping those
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different things in your head creates a cost and it keeps accumulating the
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more indirect the things are ('cause you'll have to keep all those in your
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head).
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<!-- more -->
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(Disclaimer: I like to use the expression "cognitive dissonance" to make me
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sound smarter. I usually explain what it means, though.)
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To give you an example of a (very mild) cognitive cost, I'll show you this:
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* You have a function called `sum()`. It does the sum of the numbers of a
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list.
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* You have another function, called `is_pred()`. It gets a value and, if it
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fits the predicate -- a test, basically -- returns True; otherwise,
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returns False.
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So, pretty simple, right? One function sums numbers and another returns a
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boolean.
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Now, what would you say if I shown you this, in Python:
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```python
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sum(is_pred(x) for x in my_list)
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```
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Wait, didn't I say that `sum()` sums numbers? And that `is_pred()` returns a
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boolean? How can I sum booleans? What's the expected result of True + True +
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False?
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Sadly, this works. Because someone, long time ago, didn't think booleans were
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worth a thing and used an integer instead. And everyone else since then did
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the same stupid mistake.
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But, for you, you'll now read a line that says "summing a boolean list returns
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a number". And that's two different, disparate things that you suddenly have
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to keep in mind when reading that line.
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That's why [types are important](/books/things-i-learnt/data-types) are
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important. Also, this may sound a bit like [the magical number
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seven](/books/things-i-learnt/magical-number-seven), 'cause you have to keep
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two things at your mind at the same thing but, although that's not near seven,
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they are not the same, with opposite (for weird meanings of "opposite", in this
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case) meanings.
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{{ chapters(prev_chapter_link="/books/things-i-learnt/magical-number-seven", prev_chapter_title="The Magic Number Seven, Plus Or Minus Two", next_chapter_link="/books/things-i-learnt/functional-programming", next_chapter_title="Learn The Basics of Functional Programming") }}
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